<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>哒哒的js</title>
</head>
<body>
   
    <script>

        let a = 10;
        let b = a||0;
        console.log(b);
    </script>
</body>
</html>